Google hasn't announced a launch date for Android 10, only saying that the update will arrive sometime in Q3 2019. Thanks to a Canadian carrier, though, we have an exact date to circle on our calendars.
Android 10 may launch on September 3. Rogers has an Android OS update schedule posted on its website, and as spotted by 9to5Google, the carrier briefly listed "Q OS" as coming to all of Google's Pixel phones on September 3. The Android OS update schedule has since been updated to remove any mention of "Q OS".
While not an official announcement from Google, carriers are involved in the Android OS update process, and so it's entirely possible that Google shared its planned Android 10 launch date with them while they test the update for their network. Plus, we're expecting the official Android 10 release to happen sometime soon, because the Android Q Beta 6 update that was released at the start of August was the final beta release.
Have you tried the Android 10 beta? If so, how has it been working?